Gas turbine engine fans having conventional bladed fan rotors are typically fastened directly to a downstream booster stage rotor by abutting flanges on the fan rotor and booster rotor that are bolted together. However, for some integrally bladed fan (IBF) rotors, it is difficult to access the booster rotor attachment flange. Consequently, IBF rotors are usually attached to downstream booster rotors using other configurations, which can incur a weight, design, or cost penalty.